1. Field of the Invention
The present invention relates to an ink jet apparatus which discharges ink droplets onto a recording medium for recording and has means for cleaning a wiping member used for cleaning a recording head.
2. Related Background Art
Office equipment such as computers, word processors, copying machines, etc. has been in wide use in recent years; many recording systems for their recording apparatuses have been developed. Ink jet recording apparatuses have excellent features such as easier implementation of high definition, higher speed, improved quietness, and lower cost as compared with other recording systems. However, since in an ink jet recording system, ink droplets are discharged from a recording head onto a recording medium such as paper and OHP film for recording, fine ink droplets other than discharged primary ink droplets and splashes of ink droplets discharged onto a recording medium cause so-called ink mist or the like to adhere to the discharge-port surface of a recording head; if such ink mist accumulates in a large amount around a discharge port, a discharged ink droplet is dragged by the ink around a discharge port, causing the ink droplet to be discharged in an unexpected direction different from an expected flying direction (so-called discharge deviation) and in an extreme case, a failure to discharge an ink droplet (so-called nondischarging) with a resultant deterioration in printing quality. The ink jet recording system, therefore, employs a construction that a blade formed with an elastic member such as rubber slides on a discharge-port surface for wiping off unnecessary ink droplets. If such an elastic member is employed for cleaning, at the time of wiping the discharge-port surface of a recording head, a part of wiped-off ink droplets may be splashed within a recording apparatus caused by a restoring force when the blade parts from the discharge-port surface. Also, many of wiped-off ink droplets remain adhering to the blade. If ink is left adhering to the blade, some ink is left unwiped in the next wiping operation; consequently, cleaning effect can be reduced by half, causing the aforementioned problem. Also, ink water evaporates from ink remaining adhering to the blade, causing ink viscosity to increase; as a result, foreign matter such as paper dust further adheres to the remaining ink and accumulates. If the next wiping operation is conducted under such condition, the ink with increased viscosity and foreign matter may transfer to the discharge-port surface, causing a discharge malfunction such as nondischarging or discharge deviation. Moreover, in a recording apparatus having two or more recording heads for color image recording, for example, by using ink in different colors, there has been a problem that ink which has transferred to a blade in first wiping mixes with ink of a recording head of different ink color in the next wiping of the recording head, causing a deterioration in image quality. Also, in a color ink jet recording apparatus in such construction that one blade wipes out a plurality of heads, the amount of ink adhering to the blade increases, causing an increase in adverse effect of blade contamination.
In order to solve such problems, proposed are many constructions such as a construction that the movement of a carriage is utilized for sliding an ink absorbing body against the cleaning surface of a cleaning blade after head cleaning and thereby absorbing adhering ink from the blade, a construction that in color recording, ink cleaning is conducted in the order of color deepness, from light to deep, a construction that each head is provided with a dedicated blade, and so on.
However, in the blade ink absorbing type, the installation location of an absorbing body is limited to a head carriage or the like; consequently, an absorbing body size is limited, causing a high likelihood of deterioration in capability of the ink absorbing body over in long-term use. Also, in the dedicated blade type, an increase in cost and the necessity of a large space cause an apparatus size to increase, and therefore, this type is not preferable.
Disclosed in Japanese Laid-Open Patent Application No. 62-113554 is the function of a porous body for blade cleaning and a construction that the blade cleaning porous body is brought into contact with another porous body in a home position for ink transfer. Such construction, however, has not been utilized effectively because of insufficient ink transfer from the blade cleaning porous body to another porous body.
Furthermore, in an ink jet recording apparatus which uses a so-called permanent type head, i.e. a head which is not replaced during the service life thereof, the aforementioned cleaning mechanism needs to securely perform thereof over a long term; it cannot be said that a construction fully meeting such requirement has been established.